Coronary artery disease and peripheral vascular disease can arise due to the narrowing of the arteries by atherosclerosis (also called arteriosclerosis). Coronary artery disease generally affects arteries of the heart—arteries that carry blood to cardiac muscles and surrounding tissue. Peripheral vascular disease refers to various diseases of the vascular system outside the heart and brain, which carries blood, for example, to the legs.
Atherosclerosis commonly affects the medium and large arteries, and may occur when fat, cholesterol, and other substances build up on the walls of arteries and form fleshy or hard/calcified structures called plaques/lesions. As plaque forms within the native arterial wall, the artery may narrow and become less flexible, which may make it more difficult for blood to flow therethrough. In the peripheral arteries, the plaque is typically not localized, but can extend in length along the axis of the artery for as much as 10 mm or more (in some instance up to 400 mm or more).
A number of interventional surgical methodologies may be used to treat atherosclerosis. In balloon angioplasty, for example, a physician may advance a collapsed, intravascular balloon catheter into a narrowed artery, and may inflate the balloon to macerate and/or displace plaque against the vessel wall. A successful angioplasty may help reopen the artery and allow for improved blood flow. Often, balloon angioplasty is performed in conjunction with the placement of a stent or scaffold structure within the artery to help minimize re-narrowing of the artery. Balloon angioplasty, however, can stretch the artery and induce scar tissue formation, while the placement of a stent can cut arterial tissue and also induce scar tissue formation. Scar tissue formation may lead to restenosis of the artery. In some instances, balloon angioplasty can also rip the vessel wall.
Atherectomy is another treatment methodology for atherosclerosis, and involves the use of an intravascular device to mechanically remove (e.g., debulk) plaque from the wall of the artery. Atherectomy devices may allow for the removal of plaque from the wall of an artery, reducing the risk of stretching, cutting, or dissecting the arterial wall and causing tissue damage that leads to restenosis. In some instances, atherectomy may be used to treat restenosis by removing scar tissue.
Current atherectomy treatments suffer from structural and performance limitations. For example, currently-available atherectomy devices with rotating burrs generally are not configured to capture particles that are released as the burr grinds/sands tissue, which may result in diminished downstream blood flow resulting from particle residue. Additionally, these rotating burrs may cause hemolysis, and are generally limited as an adjunct therapy to angioplasty. Other systems may include expandable cutters with foldable/movable cutting wings and vacuum-driven aspiration supplied via a vacuum pump, which may cause the artery to collapse on to the cutter and perforate the arterial wall. Other atherectomy systems may include a side-window eccentric cutter and distal nosecone which receives material from the cutter. Because the nosecone can only hold a limited volume of plaque, a surgeon may need to repeatedly withdraw the cutter and flush plaque and other material from the nosecone. It is therefore desirable to provide improved atherectomy devices and methods.